Mirkka Lahdenperä tells about elephant grannies in Live Science

Grandparents are revered in many human societies. But telling stories
about old times and overfeeding grandchildren seem like distinctly human
traits. Are these classic grandparent behaviors really limited to Homo sapiens? Do any animals know their grandparents the way people do?

Does this wee elephant know its grandparents? Credit: Shutterstock

For most species on Earth, the answer is an unequivocal no. “Usually,
there aren’t grandparents [around] anymore” when an animal is born, said
Mirkka Lahdenperä, a biologist at the University of Turku in Finland.
Even if an animal’s life span does overlap with its grandparents’, most
species spread out to avoid competing for resources, so the odds of
running into a grandparent are slim.

But there are a few notable exceptions, primarily among mammals that
live in close-knit social groups. In her book “The Social Behavior of
Older Animals” (Johns Hopkins University Press, 2009), Canadian
zoologist Anne Innis Dagg described troops of langur monkeys in India in
which older females commingled with their daughters and grandchildren. [Why Can’t All Animals Be Domesticated?]

The grandmother langurs have a particular job: They aggressively defend
the group’s infants against attacks from humans, dogs and rival
monkeys. Some female langurs even give their own grandchildren special
treatment, grooming them and stepping in when they play too roughly with
other young.

Many whale species, too, travel in family pods that include both
grandmothers and grandcalves. In groups of sperm whales, according to
Dagg, old females help babysit the group’s young while their mothers
dive for food.

Orca grandmothers often lead their pods and can live for decades after
they stop reproducing. (The oldest known orca, nicknamed “Granny,”died in 2016 at over 100.) In 2015, scientists writing in the journal Current Biology
suggested that these elder orcas help their descendants survive during
hard times, because they remember all the best places to find food.

Elephant herds are also famously matriarchal. Calves are typically born
into groups led by their grandmothers, who can live to around 80 years
old. The females in a herd form close bonds, said Lahdenperä, and
collaborate to raise their young.

In a 2016 study in the journal Scientific Reports,
Lahdenperä tried to determine if being an elephant grandmother has
evolutionary benefits. She analyzed records from a semi-captive
population of Asian elephants working for the timber industry in
Myanmar. Some adult females still lived in groups with their mothers,
while others had been moved to different areas.

Lahdenperä found that the calves of young mothers were eight times more
likely to survive if their grandmothers lived near them than if they
didn’t. When the calves’ mothers were older and more experienced at
raising babies, this beneficial “grandmother effect” disappeared even if
the actual grandmothers were still around, she found.

It isn’t entirely clear how elephant grandmothers help their
inexperienced daughters, said Lahdenperä. There’s anecdotal evidence
that they may help nurse their grandcalves,
thereby giving them a nutritional boost. But Lahdenperä thinks that the
more likely advantage is the wisdom a grandmother elephant has amassed
during her long lifetime. If a calf gets stuck in a mud pit, for
example, its grandmother might be more successful at helping the calf
than its mother would be, because she’s seen similar situations.

Indeed, most evidence for the benefits of grandparenting comes from mammals. But in 2010, researchers reported in Current Biology that in colonies of insects called gall-forming aphids (Quadrartusyoshinomiyai), older females defend their relatives after they’ve ceased to reproduce. And a 2007 study in the journal Evolution found that older female Seychelles warblers (Acrocephalus sechellensis) sometimes help their offspring raise chicks.

And what about grandfathers? Studies of humans in recent decades have
shown that a living grandfather can improve a person’s mental health and
other indicators of well-being, said Lahdenperä. But there’s no
evidence of that in the animal kingdom, she said. Male animals rarely
socialize with their own progeny, let alone any further descendants.
“Males are usually focusing on producing [more of] their own offspring,
and aren’t providing so much care,” Lahdenperä said.